Some doors of this type are exposed to the action of the wind. Various means are known for preventing major deformation which could damage the door or jam it. The vertical edges of the curtain may have a portion of greater thickness or skids fixed thereon for sliding in a channel (like sails on a boat). Vertically spaced-apart horizontal reinforcing bars are also used with their ends sliding in slideways.
The present invention relates in particular to a an industrial door having a lifting curtain and including two vertical lateral uprights each constituting or including a slideway, each slideway having a guide wall on either side of the plane of the curtain, which curtain is capable of being gathered together at the top of the door by being rolled up or folded, the curtain having lateral portions which slide in said slideways, said lateral portions being adapted to escape from the slideways in the event of an abnormal transverse force. This prevents the curtain being damaged in the event of shock.
After said lateral portions of the curtain have escaped from the slideways, it is advantageous if the curtain returns to its normal position merely by being operated and without special action being taken. To do this, it is known, in particular from Documents U.S. Pat. Nos. 1,694,314, 1,786,054, and EP-0 272 733, to provide cutouts or windows in the slideways enabling the lateral edges of the curtain to be reinserted when the curtain is raised. Unfortunately, the lateral edges can also escape from the slideways through such windows while the curtain is being lowered, particularly if the curtain is being subjected to gusting wind. A particular object of the present invention is to remedy this drawback.